/*
 起始的时间
 1980年1月1号星期二
 前面有两个空位
 一年有365 366天
 需要算出今年是365还是366
*/

var year = 2019;
var mounth = 5;
document.querySelector("#nian").innerHTML=year;
document.querySelector("#yue").innerHTML=mounth;

//总天数
var days = 0;
//判断这一年是不是闰年
function runNian(y) {
	if(y % 400 === 0 || (y % 4 === 0 && y % 100 !== 0)) {
		return true;
	} else {
		return false;
	}
}
//算1980年到现在的头一年有多少天
for(var i = 1980; i < year; i++) {
	if(runNian(i)) {
		days += 366;
	} else {
		days += 365;
	}
}

console.log(days);

//今年的一月到这个月的上一个月有多少天
/*
 31
 28
 31
 30
 */
for(var k = 1; k < mounth; k++) {
	switch(k) {
		case 1:
			days += 31;
			break;
		case 2:
			if(runNian(year)) {
				days += 29;
			} else {
				days += 28;
			}
			break;
		case 3:
			days += 31;
			break;
		case 4:
			days += 30;
			break;
		case 5:
			days += 31;
			break;
		case 6:
			days += 30;
			break;
		case 7:
			days += 31;
			break;
		case 8:
			days += 31;
			break;
		case 9:
			days += 30;
			break;
		case 10:
			days += 31;
			break;
		case 11:
			days += 30;
			break;
		case 12:
			days += 31;
			break;
	}
}

//算下一个月一共有多少天
var day = 0;
switch(mounth) {
	case 1:
		day += 31;
		break;
	case 2:
		if(runNian(year)) {
			day += 29;
		} else {
			day += 28;
		}
		break;
	case 3:
		day += 31;
		break;
	case 4:
		day += 30;
		break;
	case 5:
		day += 31;
		break;
	case 6:
		day += 30;
		break;
	case 7:
		day += 31;
		break;
	case 8:
		day += 31;
		break;
	case 9:
		day += 30;
		break;
	case 10:
		day += 31;
		break;
	case 11:
		day += 30;
		break;
	case 12:
		day += 31;
		break;
}

//算一下上个月一共有多少天
var prevDay = 0;
switch(mounth - 1) {
	case 1:
		prevDay += 31;
		break;
	case 2:
		if(runNian(year)) {
			prevDay += 29;
		} else {
			prevDay += 28;
		}
		break;
	case 3:
		prevDay += 31;
		break;
	case 4:
		prevDay += 30;
		break;
	case 5:
		prevDay += 31;
		break;
	case 6:
		prevDay += 30;
		break;
	case 7:
		prevDay += 31;
		break;
	case 8:
		day += 31;
		break;
	case 9:
		day += 30;
		break;
	case 10:
		prevDay += 31;
		break;
	case 11:
		prevDay += 30;
		break;
	case 12:
		prevDay += 31;
		break;
}

//因为 19800101是从想起而开始的 我想让他从星期日开始 所以
days += 2;
console.log(days);

//算出本月的一号是星期几（算出起始位置）
var start = days % 7;
console.log(start);

var num = 42;
//前面空多少个
//本月有多少天
//下一个月有多少天
var nextDays = num - start - day;

//取得今天是几号
var thisdate = new Date().getDate();
var date1 = document.querySelector("#date1");
for(var j = prevDay - start + 1; j <= prevDay; j++) {
	date1.innerHTML += "<span class='h'>" + j + "</span>"
}

for(var a = 1; a <= day; a++) {
	if(a == thisdate) {
		date1.innerHTML += "<span class='c'>" + a + "</span>";
	} else {
		date1.innerHTML += "<span>" + a + "</span>";
	}
}
for(var s = 1; s <= nextDays; s++) {
	date1.innerHTML += "<span class='h'>" + s + "</span>"
}